Question

How to represent double or triple bond in condensed form

Answer 1

Double bonds or triple bonds in the condensed formula should be understood by looking at the number of adjacent atoms. ie, there will be four bonds from one Carbon atom.
For example, CH3CH3 ; Here one carbon is bonded to three other Hydrogen atoms, there is only one bond left to bond with the other Carbon atom. So, it will be a single bond.
CH2CH2 ; Here one carbon is bonded to two other Hydrogen atoms, there are two bonds left to bond with the other Carbon atom. So, it will be a double bond.
CHCH ; Here one carbon is bonded to only a single Hydrogen atom, there are three bonds left to bond with the other Carbon atom. So, it will be a triple bond.